Boreholes are drilled for exploration and production of hydrocarbons, such as oil and gas. A borehole is typically drilled with a drill bit provided at the lower end of a drill string. The drill string typically includes multiple tubular segments, referred to as “drill pipe,” connected together end-to-end. The drill bit may be included with a bottom hole assembly (BHA) that has other mechanical and electromechanical tools to facilitate the drilling process. Rotating the drill bit against the formation shears or crushes material of the rock formation to drill the wellbore.
The drill string often includes tools or other devices that can be located downhole during drilling operations, such as in the BHA or elsewhere along the drill string. Remote activation and deactivation of the drill string tools and/or devices may therefore be desired. Such tools and devices include, for example, reamers, stabilizers, steering tools for steering the drill bit, and formation testing devices.
Various methods of remotely controlling downhole tool activation by controlling pressure levels of drilling fluid in the have been devised. The drilling fluid is typically “mud” that is cycled down the interior of the drill string and back up a borehole annulus. Some fluid pressure-operated reamer activation apparatuses, for example, make use of a ball-drop mechanism that permits a single activation cycle, after which a reset of the control system is needed.